The present invention relates to a method and apparatus for adjusting height of a motor vehicle.
The height of a motor vehicle is generally adjusted or controlled by a vehicle height adjusting apparatus comprising a strut type suspension mechanism operatively coupled with a suspension arm swingably connected to the vehicle. The vehicle height adjusting apparatus is operated by signals from a rotary encoder for converting vertical displacement of the suspension arm into a rotational one.
The rotary encoders are sensors for servo control systems. The rotary encoders generally includes two types. One is an incremental-type rotary encoder capable of detecting a rotational direction and displacement by detecting a two-phase pulse signal and the other is an absolute-type rotary encoder capable of detecting an absolute position by detecting a binary digit signal. In the rotary encoders of these types, the incremental-type rotary encoder is generally utilized because of the simple structure thereof and a few output lines, for example, as disclosed in the Japanese Patent Laid-open (Kokai) Publication No. 61-117414.
However, the absolute-type rotary encoder is required to prepare numbers of bits corresponding to required resolving capacity. For example, in order to discriminate the number of 256, i.e. 2.sup.8, it is required to prepare 8 bits (8 sets of photointerrupters). The preparation of the 8 bits involves problems about the location, space and excessive cost. On the other hand, the incremental-type rotary encoder can indicate the rotating direction and the increment from the initial position, but can not discriminate the absolute position.